REDUCTION OF THE DEFECT DENSITY IN HYDROGENATED AMORPHOUS-SILICON BY THERMALLY ENERGIZED GROWTH PRECURSORS

The defect density in plasma deposited hydrogenated amorphous silicon (a-Si:H) is known to be dependent on the thermal energy of growth prec ursors. The precursor temperature can be controlled independent of the substrate temperature by a mesh-type electrode placed close to the su bstrate. Energized precursors have a higher surface diffusion coeffici ent which results in a reduction of the steady-state defect density on the growth surface and hence in the film bulk. The optical band gap a nd hydrogen content depend only on the substrate temperature while the defect density is reduced drastically with increasing mesh temperatur e. Thereby, we have prepared a-Si:H having low defect density and wide optical band gap.